Water soluble cellulosic yarn produced by reacting cellulose, sulphuric acid, cyanamide, and a metal sulfate



Patented July 15 1952 I "acoztss ,vvA'rEn SOLUBLE .cELLUL' sicYAnN PRO DUCED .BY- REACTING CELLULOSE, SUL- r v SULFATE.

, PHURIC ACID, ,CYANAMIDE, A

- 1 Frank wara nraiiitiee, and Ernest Edward 'rauis,

-:--Co'v'entry England, assignorsi .to Courtaulds' a ,,Limited, London,-.England, a British company i No Drawing. Application Julfi'19 i9, Serial No: 105,058. In Great Britain July'27, 1948 n i: {This invention relates V cellulose compound which is soluble in water.

""InUnited State'sLett'ers Patent No, 2,503,261, issued November ld 19=50, we have described a process for impregnating cellu'losic textile fib'res,

yarns or fabrics withan aqueous solution containing-a non-volatile strong mineralacid and cyananiide; drying andbaking the impregnated fibres, yarns or' fabrics to efiect reaction'between the cellulose, the mineral acid and the cyanainide, I

the process beingconductedunder such conditions as to quantities,,temperatures and times that the final product contains at least 1 per cent by weightbased onthe weight of the fibres,

yarnsorufabrics of combined acid-"and preferably -a total-of at. least 3 percent-by weightof the combined acid and cyanamide together based on the weight of the: fibres, yarns or fabrics. -In carrying, out this process a definite chemical combination takes place between the. cellulose, the acid and the cyanamide throughout the body of the material. The process improves the properties :of.-the treatedmaterial's, for example, their .creaserresistance andfire-resistance sThe'j objects-of. thepresent inventionisrto prowater. l

According to the present invention cellulose material is impregnated withran aqueous. solution containing sulphuric acidand cyanarnide and the-impregnated material is treated to complete the reaction between the cellulose, sulphuric acid and cyanamide, the impregnated material containing suflicient sulphuric acid to produces, final water-soluble product which contains not less than about 25'per centby weight of combined sulphuric ,acid.

In carrying out; the process of ventiona, we 3 prefer toaddto the impregnating sulphate,

the present into the production of a I centigrade'but owing-to the dificulty of obtaining complete uniformity a'product having a combined' 'sulphuric acidcontentof at least 26 percent *to" 26.5 per cent is necessary to give solubility at 20 ce'ntigrade, although a product having a Zc'Q'rn'bined sulphuric acid content of per e'enttO"25.5 per cent will dissolve in water at-50 centigrade The amount of combined sulphur-ic acid inthe final product depends on the 25 -.duce a cellulose compound which is soluble in Th'eproc ess is preferablyscarried out'on undried regenerated cellulose material, that is cellulose material which is still in the swollen state. .J'I'he treatment-necessary to complete the-reaction between the cellulose,. sulphuric acid and amount of freesulphuric acid taken up by -the material from-the impregnating bath. Slight variations in the amount of free sulphuric-acid taken up or ch'a'nges in the concentration of suluneven drying will necessarily" "affect the solubility properties of the final product. The product-appears to be an ammonium salt of the: half ester of' sulphuric acid-and cellulose. I y Thecellulose material preferably employed is regenerated cellulose material, for example rayon fila'ments made by theuviscose process but other cellulose material; for example natural fibres such as cotton, may'be'used. With the :natural fibres the water imbibition is normally low and. it

isnnecessaryv to subject the natural. fibres to a swelling treatment with-, zfor example, caustic -.'soda, beforesubjecting them to the processor the present invention. The regenerated. cellulose material used :for carrying out-the process of the present invention'may be in the undried state,

for example undried=r."rayon, vyarn. obtained by cellulose material may also be used as the' start- 'in'g" material provided that the necessary j'steps 'a're'taken to ensure that suflicient of the impregnating' solutionistakenup by the material 'toproduce the required amount 'of combined sulphuric acid; this maybe effected; forex'arn'ple,

'by'inc'reasing the concentrations-ofthe sulphuric acid and cyanamide in the impregnating solution or by increasing the weight of solutionlefton the cellulosematerial after hydroextraction.

" The impregnation is preferably carried-out with the impregnating solution maintained below room-temperature to improve the stability of the :solution." The addition to the impregnating solution of'an alkali metal sulphate or ammonium sulphate prevents. undue degradation of the cellulose material.

After impreghation, ex'- complete the reaction between the cellulose, sul-.-

phuric acid and cyanamide. This treatment may consist of a drying step alonedr a dryingstep 31,0 is to be efiected by drying-onlyjthe 'd'rying isfollowed by a baking step. Whenthe treat'm'ent;

carried out, for example, for a period of tominutes at a temperature between85 centigrad'e contained 28.8 per cent of combined sulphuric acid.

Example 2 'Asliein-similar to tnitfused m Exa ple 1 was impregnated with an aqueous solution 27.6 per cent of cyanamide, 17.2 per cent of sulphuric acid and 100 centigrade but when the dr-ying is to be followed by baking, the dryingmay be carri'ed out for example for a period of 5 to 30,.minutes at to centigrade, and'the b'ak'inglmay be I carried out, for example, by heating at temperatures above centigrade. for exampl'efielt-LZO to 160 centigrade for 5*t'o 30 minutes. The dry- -ing .is carried out as uniformly as possible-since uneven drying, causes, soluble salts "to migrate .lfromsone partofthe material to other partspf the material. The drying may be carriedout-in "a stove with a rapidly moving current of air;

H; After the completion of -the treatment thema- --teri al is washed, to remove the-water-solublesalts,

--insolutions which will not dissolveor unduly swell the material. For example washing may be carried out in a solution containing 50 parts of s carrier,;yarn or as a core yarn in the;pr'oducti'on of'efiect'threads'or fabrics, for example the wa f teresoluble yarn may be used as 'a-Scafiolding "thread to support a. yarn fwhich not capable of withstanding" the .normal weaving process-rand --therwater-soluble L-yarnmay be subsequently re moved by washing. The water soluble' cellulose "compounds obtaine'd can also be used for the ip'r'o'ductioniof sizes by. dissolvirigithe c'ellulose compound in water and applyingrthe aqueous solution by the'usual-methods; T The size'isreadily -removed by washing.

the material. The material-is then The following'ifexampleswill'illustrate the-mes,-

-entrinvention, the parts'being by weight: V l -Ema'rnple 1 M A skein of rayonyarn weighing'to Z4Qgramis obtained froma cake madeiby'the viscose process wihichhadbeen washed but'nottdried and con taining '3'0.per cent; to 50percent o'fbone-dry cellulose was impregnated; for l ll minutesin-an aqueoussolution containing per; cent of cyanamide, 15.5.per cent orsulphuric acidyand ldd per cent of ammonium sulphate. 1 The skein was 'hydroextracted :in such a manner that the skein finally contained not. more than -28 percent-oi bone dry cellulose, driedat 54 'eentigrade' for 7 minutes andbaked at centigradefor' 10min -utes. The drying and baking werecarried out .in a stove inarapidlymoving-air current. The skeinwas washed: ina solution-containing50parts of alcohol and 50 parts of water and dried. The yarn obtained wascompletelysoluble incold wa cter. Analysis showed that the ;bone-'-d-ry-;.yarn

sulphuric acid and 30 cubic centimetres 'of and 9.3 per cent of ammonium sulphate for 10 "minutes' a't W"centigrade. The impregnated skein "was hydroextr'ated under the same conditions as *deseribedi'nExample 1 and was dried at 95 centigrade for-lomin'utes. The yarn was washed as described :inExample 1 and dried. The yarn was .ieadilyi soluble in 'cold water and contained 31.5

.. .per cnt of combined sulphuric acid.

Example -3 '"A' skein of conditioned rayon made by the vis- 'cose;process which weighed 3.41 grams was impregnated in an aqueoigs solution containing 21.9 per cent of cyanamide, 22.7 percent or sulphuric acid and 12 .4 per cent of ammoniumsulphate- ;ior 0-m .i w m ns eoe... a e extraetion for 2 minutes the -skein weighed 8.11 grams; and had absorbed1.160 grams of sulphuric acid. The skein was dried-at 70 centigrade ier 7 -minutes and then bakedat 140? centigradefor -,-10 minutes. The skein was washedas describedin Example 1 and dried. Analysis-showed that the yarn contained 27.5 per cent of ombined acid. The yarn was easily soluble in' cold water. 5

I l Example;

v A- skein of dry -co tton 'of --15ometres in-length weighing 3.09 1 grams was'immersed in=201per cent caustic soda solution for =10 minutes at "room temperature.- The skein was washed freefrom'caustic soda and was hydroextracted. The :skein weighed 6.75 grams. The skein-was impregnated in an aqueous solution prepared ?by mixing together '30 cubic centimetres of "57 per cent 'cyanamide solution, 28 'cubicicentimetres' of 52per cent sulphuric acidrand;=5 ag ra'ms :ofwammon'ium sulphate, for 10 minutes of at;0scenti'grade. The

skein was removed from i-theisolutio'n and hydroextract'ed under conditions soJtliat the sk'ein weighed 8.4 grams. The skein was dried Jat -60 centigrade for. 10 minutes Hand baked -at :1-40" centigradefor 10 minutes. The'skein waswashe'd :50 :per cent aqueous alcohol-and redi'i'e'd. The

-yarn was soluble inwateriat 50=ce'n'tig-rade'.

Example p :A skein or viscose rayo weighing 3 congrats not dried and containing about 50 percent- 6f bone dry cellulose was soaked ioi 2 to' 3 minutes -an aqueous solution' containing 18 grams or sodium-bisulpha'te, '7. cubic centimetresof 10 o'r-mal per cent solution of cyanamide. The-skein-was -hydroex'tracted,driedat-60 centigrade and baked at5 140!centigradeforr'z minutes. Th'eskei' was A 1'-: p'a'rts of water-and'then'lin'a similar solution containing .suflicient :ammonia to' neuitralise all the 'acid present "in "the yarn. "The skein was then dried; The :yarn obtained was -fire-resistant, hadlagood physical prop'erties and -was readily soluble in water.

7 V Example 6 a 1A 'sk'ein similanto that'use'din -Exam'ple impregnated with-an aqueoussolution containing -1;-2 -grams ofammonium sulphate, 13" cubic centimetres of normal sulphuric acid and 30 cubic centimetres of a 33 per cent solution of cyanamide. tracted, dried, baked and washed as in Example 1 and the skein was iinally dried. The yarn obtained was fire-resistant, had good physical properties and was readily soluble in water. Analysis The impregnated skein was hydroexshowed that the bone dry yarn contained 4.7 per cent nitrogen and 26.5 per cent of combined sulphuric acid. 7

What we claim is:

1. A water soluble yarn consisting ofthe ammonium salt of the half-ester of cellulose and sulphuric acid and containing not less than about 25% of combined sulphuric acid, acid yarn having been produced by uniformly impregnating cellulose yarn in a swollen state with an aqueous solution containing at least 15.5% of sulphuric acid, at

least 13.3% of cyanamide and a sulphate selected from the group consistingoi ammonium sulphate and an alkali metal sulphate and uniformly heating the impregnated yarn at a. temperature from 85 C. to 160 C. to completethe reaction between the cellulose, sulphuric acid and cyanamide.

2. A' process for the production of a watersoluble cellulose derivative which comprises uniformly impregnating cellulose material in a' swollen state with an aqueousvsolution containing at least 15.5% of sulphuric acid, at least 13.3%

of cyanamide and a sulphate selected from the group consisting of ammonium sulphate and an alkali metal sulphate and heating the impregnated material at a temperature from 85 C. to 160 C.'to complete the reaction between the cellulose, sulphuric acid and cyanamide so as to obtain a final product which contains not less than v 25% by weight of combined sulphuric-acid.

'3. The process of claim 2 wherein the. impregnated material is heated at a temperature between 85 and 100 centigrade for a period of 10 to 30 minutes and is thereby dried. v

4. The process of claim 2 wherein the impregnated material is heated at a temperature between and centigrade for a period of 5 to 30 minutes, with consequent drying and is thereafter baked at atemperature above centigrade for a period of 5 to 30 minutes.

5. The process of claim 2 wherein the cellulose material is regenerated cellulose filaments made from viscose. I

6. The process of claim 2 wherein the cellulose material in a swollen state'is impregnatedat below 20 0.

' FRANK WARD.

ERNEST EDWARD TALLIS.

REFERENCES CITED The following references are of record in the file of this patent:

"QUNITED STATES PATENTS Number Name Date 1,879,031 1 Becker Sept. 27, 1932 2,016,299 Schulze Oct. 8, 1935 2,033,787 Rigby Mar. 10, 1936 2,511,229 Thomas June 13, 1950 2,530,261

Morton et al. Nov. 14, 1950 OTHER REFERENCES Jorpes, J. Heparin in the Treatment of Thrombosis, 2nd Edition, Oxford University Press, 1946, pages 48, 49.

Ott, EL, Cellulose and Cellulose Derivatives, Interscience Publishers Inc.', New York city, 1943, pages 663 to 665. 

1. A WATER SOLUBLE YARN CONSISTING OF THE AMMONIUM SALT OF THE HALF-ESTER OF CELLULOSE AND SULPHURIC ACID AND CONTAINING NOT LESS THAN ABOUT 25% OF COMBINED SULPHURIC ACID, ACID YARN HAVING BEEN PRODUCED BY UNIFORMLY IMPREGNATING CELLULOSE YARN IN A SWOLLEN STATE WITH AN AQUEOUS SOLUTION CONTAINING AT LEAST 15.5% OF SULPHURIC ACID, AT LEAST 13.3% OF CYANAMIDE AND A SULPHATE SELECTED FROM THE GROUP CONSISTING OF AMMONIUM SULPHATE AND AN ALKALI METAL SULPHATE AND UNIFORMLY HEATING THE IMPREGNATED YARN AT A TEMPERATURE FROM 85* C. 160* C. TO COMPLETE THE REACTION BETWEEN THE CELLULOSE, SULPHURIC ACID AND CYANAMIDE. 